GB2177200A

GB2177200A - Sample holder for the discrete analysis of liquid preparations

Info

Publication number: GB2177200A
Application number: GB08615736A
Authority: GB
Inventors: Oswald Schiek; Anton Horn; Joachim Volke
Original assignee: Carl Zeiss Jena GmbH
Current assignee: Jenoptik AG
Priority date: 1985-07-01
Filing date: 1986-06-27
Publication date: 1987-01-14
Also published as: YU108486A; DD239473A1; DE3619107A1; HU194046B; GB8615736D0; FI862539A; HUT42703A; GB2177200B; FI862539A0

Abstract

A sample holder for the discrete analysis of liquid preparations which can also be used as a measuring cell, which ensures the same layer thickness of all the samples in it and which is temperable and easy to clean includes a central body (1) which contains cavities (7) and which is bounded by a lower terminal element (4) at the bottom and an upper recessed terminal element (5) at the top, these terminal elements (4, 5) having surfaces lying in respective common planes which are at least in the vicinity of the bottom and top surfaces (2, 3) of the central body (1). The central body (1) may include passages for temperature control means (Fig. 3) between the central body (1) and the power element (4) there may be a sheet carrying analysis reactants ((22). Fig. 4c not shown). <IMAGE>

Description

SPECIFICATION Sample holder for the discrete analysis of liquid preparations to be analysed The invention relates to a sample holder for the discrete analysis of liquid preparations to be analysed preferably for use in chemical, enzymatic and immunological analyses in biological research, clinical chemistry and laboratory diagnosis, for analytical tasks in, for example, animal and plant breeding, in microbiology, immunobiology and tropical medicine.

Such a sample holder is to be used mainly in cases in which large quantities of samples are to be tested by photometric methods (colorimetrically, fluorimetrically, turbidimetrically and nephelometrically).

Microtitration plates are known comprising a matrix-like compound arrangement of sample receptacles have the advantage of being very practical with regard to sample coating and to layer thickness, which is freely selectable within the height of the plate and which is given by the volume of the analysis preparation. They have, however, the following disadvantages.

As a result of the varying optical effect of the free light-bordering surfaces in the different cavities, there is no constant opticai ray path.

Variations in adhesive bonding of the analysis preparation to the vessel walls, volume errors and deviations in the geometric parameters of the individual vessels all influence the ray path of the light in the photometer, the precision of the layer thickness and hence the quality of the analysis results.

The range of application of microtitration plates is thus considerably restricted.

Sample holders of the microcell type as, for example, described in East German Patent Specification No. 107783, have the advantage of a precisely determined layer thickness and allow photometric measurement of extremely small sample quantities with a high degree of accuracy.

However, a disadvantage of these known cells is that, as a result of the lack of a lateral boundary in the individual sample locations, the application of solutions containing detergent and having a low surface tension requires extreme care. Furthermore, the layer thickness is limited to a maximum of 2 to 3 mm, which restricts the testing of samples having a low coefficient of absorption by colormetric and turbidimetric measurement.

Both these types of cell have the common disadvantage that they are extremely hard to temper and hence cannot be used for enzymatic measurement.

It is the basic aim of the invention to enable precise colormetric, fluorimetric, nephelometric and turbidimetric measurement for discrete analysis of a plurality of preparations to be analysed in an analysis block and to provide a wide range of application for the measurement methods.

A specific object of the invention is to develop a sample holder for liquid samples, which can also be used as a measuring cell, which is easy to use, ensures a defined layer thickness which is advantageous for photometric analysis and which is the same for all the samples in the sample holder, and which can be tempered and easily cleaned.

In accordance with the present invention there is provided a sample holder for the discrete analysis of liquid analysis preparations, comprising a central body which contains a plurality of cavities and whose bottom and top surfaces form boundary planes defining opposite ends of the cavities, said top and bottom surfaces of the central body being bounded by a lower terminal element and an upper terminal element, respectively, recesses being provided in that side of the upper terminal element which faces the central body, these recesses defining lands made of an optically transparent material which lies in a common plane and which correspond in number and arrangement to the cavities in the central body and at least partially terminate these cavities, the lower terminal element having surface elements lying in a common plane and closing off the bottom ends of the cavities in the central body, and said common planes being parallel to the bottom and top surfaces of the central body, at least in the vicinity of the areas associated with them.

Different forms of upper terminal element are provided depending on the surface tension of the analysis preparations.

In a first embodiment, the regions defined by the recesses are in contact with the preparations to be analysed in the cavities by way of spacers disposed between the central body and the upper terminal element in such a way that the analysis preparations in the part between the central body and the upper terminal element are bounded on one side by air only.

In another embodiment, the areas defined by the recesses form spigots made of optically transparent material and partially projecting into the cavities with lateral play.

If a terminal element according to the first variant is used, it is advantageous to work recesses into the top surface of the central body which surround the cavities with clearance and lie substantially opposite the recesses in the upper terminal element.

For easy cleaning, it is advantageous if the lower terminal element is made of an optically transparent, flexible material and a pressure plate adapted to match the profile in the region of the bottom surface of the central body.

The flexible material can at the same time be provided with coreactants for an analysis operation.

In a further solution according to the invention, the cavities are in the form of tubes of equal length let into the central body and having calibrated inner diameters, whose ends lie in common planes which are parallel to the bottom and top surfaces of the central body, at least in the proximity of the associated surface.

In order to temper the sample holder according to the invention, the central body, which is made of a heat-conducting material, is provided with further interconnected cavities which surround the first mentioned cavities at least partially, are provided with at least one passage through the central body to the outside and which contain means for measurable and controllable tempering.

If the sample holder according to the invention is to be heatable, at least the bottom or top surface or a cross-sectional area of the central body can be covered with a currentconducting material which leaves the cavities free.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective representation of the individual element of one embodiment of a sample holder according to the invention; Figure 2 shows a sample holder having an upper terminal element for analysis substances having low surface tension; Figure 3 is a side view of a temperable central body; and Figure 4 a-d are side views of parts of a sample holder with tubes let into the central body.

The sample holder shown in Fig. 1 comprises a cuboid central body 1, having optically transparent terminal elements 4, 5 disposed adjacent to its bottom and top faces 2, 3, respectively. Recesses are worked into the top surface 3 in the form of grooves 6 which surround cylindrical cavities 7 of the central body which are arranged in a matrix-like manner. The bottom and top surfaces 2, 3 form the boundary planes of the cavities 7.

Of the two terminal elements 4, 5 adjacent to the central body 1, the upper one is provided with recesses in the form of grooves 8 which are substantially opposite the grooves 6 and define lands 9 lying in a common plane.

The lower terminal element 4 can, for example, be removable by way of mechanical or magnetic means (not shown) or can be firmly secured to the central body 1.

To perform analysis, the cavities 7, which are sealed off at the bottom by the element 4, are filled with liquid preparations for analysis using a correspondingly constructed pipetting device so that convex liquid meniscuses project above the upper edge of the cavities 7 (the upper edge of the cavities 7 corresponds in Fig. 1 to the top surface 3).

Spacers 10 provided on the top surface 3 are designed such that when the terminal element 5 is placed on them, its lands 9 enclosed by the grooves 8 are in contact with the liquid meniscuses.

As a result of the zone delimitation effected by the grooves and the cohesive and adhesive effect- the analysis preparations are bounded on the side by air only in the meniscusis part-, the liquid is kept stable and running is avoided. At the same time, all the liquid columns in the hollow cylinders have a constant layer thickness due to their being closed at the top.

The sample holder is put into a correspondingly designed photometer and a successive or simultaneous analysis is carried out. The use of the upper terminal element shown in Fig. 1 requires the liquids to be tested to have a sufficient surface tension. If this does not exist, then the technical solution shown in Fig.

2 can be used, in which the recesses in the upper terminal element 5 are such that spigots 11 are formed with boundary surfaces 12 lying in one plane. The central body 1 is further defined by a terminal element comprising a plane parallel plate 13 and a pressure plate 14. Additional sealing elements prevent the analysis preparations for leaking or being mixed up.

This solution for the lower terminal element can also be used in the solution shown in Fig.

1.

By immersing the spigots 11 in the analysis substance in the cavities 7, the actual layer thickness of the substance to be photometrically evaluated is determined by the gap between the boundary surfaces 12 and the bottom surface 2. Lateral play between the spigots 11 and the walls of the cavities 7 enables excess substance to be expelled.

The filling height of the analysis substance must be selected so that when the spigots 11 are immersed in the liquid, it does not overflow.

By using different upper terminal elements 5 having spigots 11 of different length, different layer thicknesses can be realised using the same central body.

The central body 1 shown in Fig. 3 has, for example tempering, further cavities 16, which at least partially surround the cavities 7 and which are interconnected by means (not shown). The cavities 16 can be designed for the passage of tempering fluid or to accommodate heating and temperature measuring devices. Passages 17, 18 are connected to the cavities 16 and serve as inlets and outlets or as inlet openings for electric leads. A further method of tempering the samples is obtained by covering the bottom and/or top surface of one or more cross-sectional areas with a current-conducting material, leaving the cavities free.

In Figs. 4a-d, the cavities 7 are in the form of tubes 19 let into the central body, whose tube ends 20, 21 form respective common planes (not shown) which are parallel to the bottom and top surfaces 2, 3. The common planes either coincide with the bottom or top surfaces 2, 3 (a) or are offset therefrom (b-d).

Whereas in the solution according to Fig. 4a, grooves 6 are worked into the top surface 3, as already shown in Fig. 1 an equivalent effect to that of the grooves 6 is achieved by the elevation of the tube ends 21 relative to the top surface 3 (Fig. b-d).

The staggering of the plane formed by the tube ends 20 relative to the bottom surface 2 forms a profile which allows a lower terminal element to be used which is composed of a sheet 22 of optically transparent, flexible material and a pressure plate 23 adapted to the profile. The sheet is joined to the profile of the main body 1 by the pressure plate 23, thus sealing off the tubes 19, wherein the pressure plate 23 is secured mechanically or magnetically. This solution permits easy cleaning of the sample holder by removing the sheet 22 and replacing it with a new one. If necessary, it is possible to provide the side of the sheet 22 facing the central body, or at least those parts closing off the tubes 19, with coreactants for analysis.

Claims

1. A sample holder for the discrete analysis of liquid analysis preparations, comprising a central body which contains a plurality of cavities and whose bottom and top surfaces form boundary planes defining opposite ends of the cavities, said top and bottom surfaces of the central body being bounded by a lower terminal element and an upper terminal element, respectively, recesses being provided in that side of the upper terminal element which faces the central body, these recesses defining lands made of an optically transparent material which lie in a common plane and which correspond in number and arrangement to the cavities in the central body and at least partially terminate these cavities, the lower terminal element having surface elements lying in a common plane and closing off the bottom ends of the cavities in the central body, and said common planes being parallel to the bottom and top surfaces of the central body, at least in the vicinity of the areas associated with them.

2. A sample holder as claimed in claim 1, wherein, in use, the regions defined by the recesses are in contact with the preparations to be analysed in the cavities by way of spacers disposed between the central body and the upper terminal element in such a way that the analysis preparations in the parts between the central body and the upper terminal element are bounded on one side by air only.

3. A sample holder as claimed in claim 1, wherein the regions defined by the recesses are in the form of spigots made of optically transparent material which partially project into the cavities in the central body with lateral play.

4. A sample holder as claimed in claim 2, wherein recesses are provided in the top surface of the central body which surround the cavities with clearance and lie substantially opposite the recesses in the upper terminal element.

5. A sample holder as claimed in any of claims 1 to 4, wherein the lower terminal element comprises an optically transparent, flexible material and a pressure plate adapted tomatch the profile in the region of the bottom surface of the central body.

6. A sample holder as claimed in any of claima 1 to 5, wherein the cavities are in the form of tubes of equal length and calibrated inner diameters let into the central body, the opposite ends of the tubes lying in respective common planes which are parallel to the bottom and top surfaces of the central body, at least in the proximity of the associated surfaces thereof.

7. A sample holder as claimed in any of claims 1 to 6, wherein the central body is formed of heat-conducting material and is provided with further interconnected cavities which surround the hollow cylinders at least partially, the latter cavities being provided with at least one passage through the central body to the outside and which contain means for measurable and controllable tempering.

8. A sample holder as claimed in any of claims 1 to 6, wherein at least the bottom or top face or an intermediate cross-sectional area of the central body is covered with a current-conducting material which leaves the cavities free.

9. A sample holder as claimed in claim 5, wherein the face of the part of the covering body which is made of an optically transparent, flexible material and which faces the central body is provided with coreactants for analysis.

10. A sample holder, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.